1. Field of the Invention
The present invention relates to a laptop computer with an anti-theft alarm function, and more particularly, to a laptop computer capable of generating an anti-theft alarm in accordance with a switching signal occurring upon a liquid crystal display (LCD) on/off switch being operated by an unauthorized user and a method of controlling the same.
2. Description of the Related Art
In general, a typical laptop computer has several kinds of functions, such as the turning on/off of an LCD back-light section, a password procedure and a locking/unlocking mode.
A laptop computer is known to be provided with an LCD on/off switch and a keyboard, and LCD cover having an LCD screen, and a main computer body having a front panel for pivotally mounting the keyboard. Such a computer further includes an LCD on/off switch installed on the front panel of the body and capable of turning the LCD screen on or off and a switch compressing projection installed on the LCD cover and capable of pushing down on the LCD on/off switch when the LCD cover is pivotally folded over the upper panel of the main computer body.
If such a laptop computer is not supplied with an externally supplied power source, it may be operated with an internal battery until the internal battery is completely discharged. It is well known in the art that a back-light section of the LCD screen consumes more power than any of the other components of the computer. For this reason, most laptop computers are provided with a power saving circuit to prevent an excessive power consumption during the operation thereof. The power saving circuit allows for the interruption of the supply of power from the battery to the backlight section of the LCD screen when the computer is not in use for a predetermined time, such as, when there is no data provided from the keyboard or a mouse or when the LCD cover is pivotally folded over the main computer body, that is, the LCD on/off switch is pushed down by the switch compressing projection.
In the latter case, battery power can be saved by switching off the back-light section of the LCD screen.
When the switch on the computer is switched off to turn the LCD back/light section off when the LCD cover is pivotally folded over the main computer body, a microcomputer contained within the laptop computer receives data from the keyboard and/or a switching on/off signal from the switch to generate a control signal. A controller for turning the LCD back/light section of the LCD cover on and off in response to the control signal from the microcomputer and a power supply controller for supplying power to the main computer body and the LCD screen and for changing from a previous power mode to a power saving mode in response to the control signal from the microcomputer are also contained within the laptop computer. If the LCD on/off switch is pushed down during the operation of the computer, the microcomputer provides the control signal to the controller to turn the LCD back-light section off. Then, the power supply controller controls the power to the computer and effects a power saving mode in response to the control signal.
The above noted computer may have a password identification function for identifying a previously set password by a user every time it is reset and restarted. This password identification function is provided in the computer to prevent any other person from changing the computer environment which has been previously set by a user. If a password entered by a user is not identical with the previously set password, the laptop computer with the above noted password identification function can not be operated by the unauthorized user. This function may also be performed only in case of a cold booting operation or a warm booting operation. Thus, by such a password identification function, other unauthorized users can not use the computer.
Even when an unauthorized user operates the computer for the purpose of altering the user environment thereof including the previously set password during an authorized user's absence, the computer requires the input of a previously set password at the beginning of the operation thereof. Thus, if a password which is the same as the previously set password is not entered, the computer can not be used by the unauthorized user. The authorized user can, however, enable or disable the password identification function of the computer, and change the password, if necessary.
In addition, the laptop computer further includes an anti-theft function, which is composed of a mechanical and physical locking system therein.
Since the above described functions are independently performed in the computer, the abovenoted computer has some problems in that it can not be prevented from being moved against the user's will and in that it's functions can not be performed simultaneously with one another.
The following patents each disclose features in common with the present invention but do not teach or suggest the specific combination of a laptop computer in which an alarm is sounded when the computer is opened or closed, thereby turning on or off its liquid crystal display, the alarm being turned off by the entry of the proper password on the keyboard of the computer as in the present invention:
U.S. Pat. No. 5,138,299 to Pattern el al., entitled Showcase Alarm System, U.S. Pat. No. 5,578,991 to Scholder, entitled Security System And Method For A Portable Personal Computer, U.S. Pat. No. 4,939,706 to Nose, entitled Transaction Processing Apparatus With A Monitor System For Monitoring Drawer Opening And Closing Conditions, U.S. Pat. No. 4,951,249 to McClung et aL, entitled Method And Apparatus For Controlled Access To A Computer System, and U.S. Pat. No. 4,347,566 to Duwel et al, entitled Electronic Postage Meter Having Check Date Warning With Control For Overriding The Check Date Warning.